Apparatus for dewaxing and dehydrating refrigerants



Dec. 11, 1951 E. A. WENK 2,577,834

APPARATUS FOR DEWAXING AND DEHYDRATING REFRIGERANTS Filgd March 19; 1948ayz ' Y INVENTOR.

fimo a. @144 @FM Q Patented Dec. 11, 1951 U D STATES PATENT: OFFICE YAPPARATUS FOR DEWAXING AND DEHY DRATIN G BEFRIGERAN TS Edward A. Wenk,New York, N. Y.

Application March 19, 19.48, SerialNo. 15,756

1 Claims. (01. 62. 115) l This'invention relates to apparatus fordewaxing and dehydrating refrigerants such asareusedincompressor-condensor evaporator refrigeration I systems. i

The most common of such refrigerants used commercially are of the groupknown as halide refrigerants or substituted hydrocarbon refrigerants,such as Freon 12 (CC12F2) and methyl chloride (CI-I301). For many year.irregularities in the operation of liquid control valves handling suchrefrigerants were blamed primarily on moisture and to remove thismoisture; which was believed to freeze and interfere with the operationof the expansion valve, a dehydrator was installed in the liquidrefrigerant line feeding the expansion valve, usually near the liquidreceiver. Such a dehydrator was usually a capped-section of tubingprovided with suitable connections on both ends to attach it to the lineand containing an adsorbent. such as calcium oxide, silica gel,activated alumina or calcium chloride. The adsorbent was confined withinthe dehydrator by suitable. filter pads or screens.

My investigation of the problem of such irregularities of the action ofexpansion valvesv in refrigeration systems indicated little evidencethat moisture had been present or thatait was a -primary cause of. suchirregularities. This investigation further led to the conclusion thatsuch irregularities were due primarily to. a wax which forms in the oilin the compressor.. This waxy substance was found in. the compressorsand expansion valves and is characterizedby being soluble only in toluoland. as having a, very low melting point, in the order of 607 to 70 F.This, wax

also seems to adverselyaffectgthe. lubricating,

qualities of the refrigeration oil at temperatures of from 70 to 110 F.,this being the usual temperature range of the lubricant inarefrigeration compressor.

The above practice of installing a dehydrator in the liquid refrigerantfeed line between the liquid receiver and the expansion valve. butusually right next to the condenser, has. not-proved satisfactorybecause. of the wide temperature. range. of liquid refrigerant t hisnointand thehigh tem: perature of, the surrounding air as well as theheat derived by conduction. from. thecondenser. Because. of the hightemperature of the denydrator at this location it isnot possible toremove any wax from the refrigerant passing through it and it is alsopossible to remove but little ofv the moisture. "The principal object ofthe presentv invention is. to provide a simpleand efficient apparatus='for 2 thereby to improve the performance of the expansion valve aswell as to improve the lubricating effectv of the oil in the compressor.

Another object is to provide. such apparatus which-dehydrates thelubricant in addition to dewaxing the same. i

Another object is to provide such apparatus in which the rate ofadsorption of the moisture is substantially increased;

Another object is to provide such apparatus in which the capacity of themoisture adsorbent or desiccant is substantially increased.

Another aim is to provide such apparatus in which all wax present in therefrigerant is precipitated and readily removable.

Anctherobject is to provide such apparatus in which a substantialoverall increase in the capacity of the condenser and evaporator canbeobtained.

Another aim is to provide such apparatuswhich serves to entrain andremove from the refrigerant all dirt, scale or other foreign matter.

Another object is to provide such apparatus which is low-in cost andtrouble-free in operation and. which will stand up under conditions ofsevere and constantusewithout requiring repair.

Qther objects and. advantages of the invention will appear from thefollowing description and drawings in which:

Fig. l is a diagrammatic representation ofcompressor-condenser-evaporator refrigeration apparatus embodying thepresentinvention.

Fig. 2 is an enlarged vertical section through a dewaxing anddehydrating unit used in the apparatusshown in Fig. 1. a

Fig. 3 is a fragmentary view similar to Fig.- -1 and showing a modifiedform of the invention.

Referring to Fig. 1, the numeral 5 represents anevaporator connected bya suction line 6 with a compressor 8 the outlet of which is connected toa condenser 9. The discharge line from the condenser 9 connects with areceiver Ill the liquid .line- H fromwh-ich connects with the centraldwaxing the refrigerant in a refrigeration system chamber I42 ofva-dewaxing and dehydratingv unit -13 forming apart of the presentinvention. From thechamber l 2. of the dewaxing and dehydrating.

ingand dehydratinaunit I3. Fig. 1- shows a con- I ventionalcompressor-condenser -evapel'ator re frigeration-system. pThis--dewaxing and dehydrating unit I3 is shown in detail in Fig. 2 andas there shown includes an inner tubular shell 20 enclosed by upper andlower end heads H to provide the central chamber I2 through which theliquid refrigerant passes to the expansion valve I5 as previouslydescribed. Each of the end heads 2| is formed. to provide an outwardlyprojecting, internally threaded flare fitting socket 22 having anoutwardly facing conical seat 23 at its inner end surrounding an openingcommunicating with the interior central chamber I2. In each of thesesockets 22 is arranged the enlarged outwardly flaring concave-convex endflange 24 of a tubular screen 25, the flange of this screen fittingagainst the seat 23 of the corresponding socket 22 and the screen 25projecting into the central chamber I2 and being closed at its innerend. Each screen, is retained in place by a reducing flare union 25, theenlarged externally threaded end of which screws into the correspondingsocket 22 against the enlarged outwardly flaring concavo-convex flange24 of the screen therein and the reduced externally threaded end ofwhich is connected by the usual flare fitting to the flared end of thecorresponding liquid refrigerant line. The reducing flare union 25 atthe upper end of the dewaxing and dehydrating unit connects with theliquid line II from the receiver I and the reducing flare union at thelower end of the unit connects with the liquid line I 4 leading to theexpansion valve I5. At the suction or outlet end of the unit the tubularscreen 25 can be internally supported against collapse by a helicalspring 23.

The chamber I2 so provided with the tubular screens 25 at its inlet andoutlet is filled with a suitable solid desiccant or adsorbent 29 ingranular or lump form to remove the moisture from the liquid refrigerantpassing therethrough. This can be in the form of silica gel, activatedalumina, calcium oxide, calcium chloride or the like. However, the useof such desiccant or moisture adsorbent is only necessary where removalof the moisture from the refrigerant is desired and if only wax removalis required the filler 29 in the inner chamber I2 can be in the form ofmetal wool, felt, porous stone or suitable baflles to effect the desiredheat transfer.

The tubular shell 20 is enclosed by a jacket 30 which is shown as havingan inlet 3I at one side connected in any suitable manner with the outletof the expansion valve I and as having an outlet 32 at its other sideconnected in any suitable manner with the inlet of the evaporator -col-l5.

In the operation of the apparatus as above described, the refrigerant iscompressed in the compressor 8, is liquefied in the condenser 9 andpasses through the receiver I II, liquid line II. upper union 26, andupper tubular screen 25 into the inner chamber I2 of the dewaxing andde- This adsorbent is maining in the Jacket space I5 and at this lowtemperature all of the wax within the passing refrigerant congeals uponthe adsorbent 29. This adsorbent further acts as a desiccant to abstractthe moisture present in the passing refrigerant. At this low temperatureof the assumed 35 F.

the rate of adsorption of this moisture is high as compared with thehigh temperatures present in conventional dehydrators arranged inadvance of theexpansion valve I5. Further, at

this low temperature the capacity of the adsorbent 29 as a drying agentis increased by 16% or more as compared with conventional dehydratorsconventionally located and operating at a higher temperature. Theimportant feature of the low temperature at which the adsorbent ismaintained, however, resides in its capacity to discharges therefrigerant as a high pressure gas through the inlet 3I into the jacketspace I5 of the dewaxing and dehydrating unit I3 thereby to maintain thelow temperature of the adsorbent 29 therein as previously described. Thegas then passes from ,the outlet 32 to the expansion coil 5 from whichthe gaseous refrigerant returns through the suction line 5 to thecompressor.

The above arrangement provides the maximum effect in dewaxing anddehydrating the refrigerant. At a slight sacrifice in this regard thedewaxing and dehumidifying unit I3 can, however, be additionallyemployed asa heat ex"- changer by arranging it at the outlet of theevaporator 5 as shown in Fig. 3 instead of at its inlet as shown inFigs. 1 and 2. With the dewaxing and dehydrating unit located as shownin Fig. 3, the low pressure gas from the evaporator 5 passes through theadsorbent contained within the central chamber I2 and which ismaintained at the assumed low temperature of 35 F. by liquid refrigerantfrom the expansion valve I5 entering the jacket space I5 from a line 35and leaving this jacket space through a line 35 connected with the inletof the evaporator 5. By so utilizing the dewaxer and dehydrator l3 as aheat exchanger at the outlet end of the evaporator as shown in Fig. 3 anincrease in the capacity of the condenser 9 of from 5 to 10% isachieved.

It will be apparent that many changes in the construction of thedewaxing and dehydrating unit I3 can be made without departing from theinvention. In particular any form of heat exchange devices can beemployed as by fastening the inner shell 20 directly to the highpressure line from the expansion valve I5 to the evaporator 5 .insteadof jacketing this shell as shown. The invention is therefore not to beregarded as limited to the specific features shown but is to be accordedthe full range ofequivalents compree hended by the following claims.

I claim:

1. In refrigerating apparatus having a compressor, condenser, expansionvalve and evaporafor through which an expansible refrigerant isrecirculated in series, the combination therewith of means for dewaxingthe refrigerant so recirculated comprising a body forming a flrstchamber connected with one end of said evaporator and containing adesiccant and through, which said refrigerant passes and formed toprovides second chamber in heat exchange relation with said firstchamber, and means arranged to pass the expanding refrigerant from saidexpansion valve to said evaporator through said second chamber inheatexchange relation with said first chamber to cool the refrigerantpassing there'- through to a temperature at which the wax containedwithin the refrigerant congeais therein.

2, In refrigerating apparatus having a compressor, condenser, expansionvalve and evaporator through which an expansible refrigerant isrecirculated in series, the combination therewith of means for dewaxingthe refrigerant so recirculated comprising a body forming a firstchamber connected with the inlet end of said expansion valve and.through which said refrigerant passes and formed to provide a secondchamber in heat exchange relation with said first chamber, and meansarranged to pass the expanding refrigerant from said expansion valve tosaid evaporator through said second chamber in heat exchange relationwith said first chamber to cool the refrigerant passing therethrough toa temperature at which the wax contained within the refrigerant congealstherein.

3. In refrigerating apparatus having a compressor, condenser, expansionvalve and evaporator through which an expansible refrigerant isrecirculated in series, the combination therewith of means for dewaxingthe refrigerant so recirculated comprising a body forming a firstchamber connected with the outlet end of said evaporator and containinga desiccant and through which said refrigerant passes and formed toprovide a second chamber in heat exchange relation with said firstchamber, and means arranged to pass the expanding refrigerant from saidexpansion valve to said evaporator through said second chamber in heatexchange relation with said first chamber to cool the refrigerantpassing therethrough to a temperature at which the wax contained withinthe refrigerant congeals therein.

4. In refrigerating apparatus having a compressor, condenser, expansionvalve and evaporator through which anexpansible refrigerant isrecirculated in series, the combination therewith of means for dewaxingand dehydrating the refrigerant so recirculated, comprising a bodyforming a first chamber connected at one end with said evaporator andthrough which said refrigerant passes and. formed to provide a secondchamber in heat exchange relation with said first chamber, a desiccantconfined within said first chamber and contacted by said refrigerant,and means arranged to pass the expanding refriger ant from saidexpansion valve to said evaporator through said second chamber in heatexchange relation with said first chamber to cool said desiccant and therefrigerant passing in contact therewith to a temperature at which thewax contained within the refrigerant congeals on said desiccant.

5. In refrigerating apparatus having a compressor, condenser, expansionvalve and evaporator through which an expansible refrigerant is irecirculated in series, the combination therewith of means for dewaxingand dehydrating the refrigerant so recirculated, comprising a bodyforming a first chamber connected with the inlet of said expansion valveand through which said refrigerant passes and formed to provide a secondchamber in heat exchange relation with said first chamber, a desiccantconfined within said first chamber and contacted by said refrigerant,and means arranged to pass the expanding refriger ant from saidexpansion valve to said evaporator through said second chamber in heatexchange relation with said first chamber to cool said desiccant and therefrigerant passing in contact therewith to a temperature at which thewax congeals on said desiccant.

6. In refrigerating apparatus having a compressor, condenser, expansionvalve and evaporator through which an expansible refrigerant isrecirculated in series, the combination therewith of means for dewaxingand dehydrating the refrigerant so recirculated, comprising a bodyforming a first chamber connected with the outlet of said evaporator andthrough which said refrigerant passes and formed to provide a secondchamber in heat exchange relation with said first chamber, a desiccantconfined within said first chamber and contacted by said refrigerant,and means arranged to pass the expanding refrigerant from said expansionvalve to said evaporator through said second chamber in heat exchangerelation with said first chamber to cool said desiccant and therefrigerant passing in contact therewith to a temperature at which thewax congeals on said desiccant.

7. In combination with a refrigeration apparatus, an expansion valve, acasing into which refrigerant on its way to the evaporator is expandedfrom said valve, a conduit traversing said casing and being in heatexchange relation therewith, means for supplying liquid refrigerant tosaid conduit, means for conducting said liquid refrigerant from saidconduit to the inlet of said valve, and refrigerant filter means in saidconduit.

EDWARD A. WENK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,073,863 Bird Mar. 16, 19372,199,258 Gray Apr. 30, 1940 2,230,892 Miller Feb. 4, 1941 2,243,949 FoxJune 3, 1941 2,279,928 Shoemaker Apr. 14, 1942 2,285,123 Phillips June2, 1942 2,341,430. Elsey Feb. 8, 1944 2,430,692 Touborg Nov. 11, 1947OTHER REFERENCES Article in the Ice and Refrigeration magazine entitledExpansion Valves, July 1946 issue; pages 33 through 36.

